Generally, items to be wrapped must be wrapped with a material that will be strong enough to hold the item from falling apart but also prevent liquids or moisture from penetrating the item, which could cause permanent damage. For all types of wrapping applications, the wrapping material is required to have the following basic characteristics: 1) it must hold the wrapped item securely and prevent liquids or moisture, such as rain, from penetrating the wrapped item; 2) it must be feedable into a wrapping machine without sticking to the pulling rolls along the wrapping material's path; and 3) it must hold or adhere to the item to be wrapped and also adhere to the wrapping material directly beneath it, if necessary.
There are a number of materials that have been proposed for wrapping items, but all have drawbacks. For example, netting materials have many advantages with regard to strength and the ease of use, but cannot prevent penetration of liquids. On the other hand, wrapping film effectively protects against moisture but is required to have adhesive qualities, and such a film has difficulty being fed into existing wrapping machines, for example, round balers manufactured for wrapping with netting. Moreover, wrapping material formed from existing laminate combinations of netting with cling film also experience problems when used with existing wrapping machines because the laminate cannot be successfully fed into these machines because of the characteristics of the cling film.
In order to avoid this problem, complicated and expensive devices have been built to enable the wrapping of items with these types of wrapping materials. The following prior art references give examples of existing wrapping techniques used for baled items. U.S. Pat. No. 4,366,665, U.S. Pat. No. 4,956,968 and International Patent Application Patent No. WO 00/64237 disclose a baler with an apparatus for supplying plastic film to a completed bale. However, none of these references disclose a wrapping method or material that combines the advantages of wrapping with different types of material in a single wrapping process.
U.S. Pat. No. 4,703,605 discloses a method of baling using different wrapping materials. The wrapping material includes a shape retaining wrapping web that completely surrounds the circumference of the bale, and a water impermeable wrapping material extending over a portion of the circumference of the bale. The water-impermeable material includes a foil material that is introduced into the wrapping process so as to cover predetermined portions on the top and bottom of the bale. The portion at the top protects the bale from rain, and the portion at the bottom protects the bale from moisture on the ground. Although this wrapping process attempts to take advantage of using different materials to wrap a bale, it fails to provide a continuous wrapping material composed of multi-material segments that can be easily applied to existing wrapping technologies.
Examples of “Prior Art” wrapping are shown in FIGS. 1 and 2. FIG. 1 illustrates a prior art wrapping material 2 used to wrap an item 3. The prior art wrapping material includes two layers 5A, 5B of different material types that are joined together to form a laminate. For example, for baling items such as hay, the first layer 5A would typically be a netting material that would hold the bale together and the second layer 5B would be a plastic wrap used as a moisture barrier to protect the baled hay from moisture damage. If the baled item were cotton, the first layer 5A may be a non-cling film instead of a netting material. However, regardless of the application, the layers 5A, 5B would typically be combined as a laminate material prior to or during the wrapping process using a different wrapping apparatus. Thus, the prior art processes requires extensive modification to existing baling machinery, such as the installation of special devices to enable use of cling film. For example, a hay baler that works with only netting would have to be modified to a baler that also works with cling film, or in the alternative an entire new system would have to be built to work in conjunction with an existing hay baler. However, progress has been slow because of the difficulty in matching the netting and film using different wrapping devices during the wrapping process.
FIG. 2 is a more detailed illustration of the different layers of the prior art wrapping material previously mentioned and a method of making the wrapping material. The prior art wrapping material 5 includes two layers 5A and 5B that are combined during the material's manufacturing process as a laminate as shown in FIG. 2. When used as a laminate, the first layer 5A is attached to the second layer 5B using a method of bonding known in the art. For example, by using a permanent adhesive the layers are bonded/adhered to each other with or without the application of heat. Alternatively, pressure can be applied to the layers during manufacture, which will bond layers 5A, 5B to one another. Thus, during the wrapping process the layers of the laminate are wrapped around the circumference of the item simultaneously as a single sheet of wrapping material. However, whenever there are two elements so bonded together (i.e., as a co-extensive laminate) that are not identical in their characteristics, the resulting combination will include the negative qualities of each of the materials used. For example, if film has a greater tendency than netting to narrow (“shrinkage”), then when the film shrinks it will also cause the attached netting to shrink as well.